The Human Immunodeficiency Virus (HIV) has now been established as the causative agent of the Acquired Immunodeficiency Syndrome (AIDS) for over 20 years (Science 1983, 220, 868-871; N. Eng. J. Med. 1984, 311, 1292-1297). AIDS is characterized by the destruction of the immune system, particularly of CD4+T-cells. HIV is a retrovirus, and the HIV life cycle encompasses several crucial steps, starting from the attachment of the virus to the host cell membrane and finishing with the release of progeny virons from the cell.
The natural compound betulinicacid acid, isolated from Syzygium clavifolium and several other plant species was found to possess anti-HIV activity. Chemical modifications were undertaken by several research groups in an attempt to identify potent anti-HIV agents by making semi-synthetic analogs of betulinic acid, leading to the discovery of bevirimat as a compound with a novel mechanism of action (J. Nat. Prod. 199457(2):243-7; J. Med. Chem. 1996, 39(5), 1016). Further studies shown that bevirimat acts by disrupting Gag processing (Proc. Natl. Acad. Sci. USA 2003, 100(23):13555-60; Antimicrob. Agents. Chemother. 2001, 45(4), 1225-30; J. Virol. 2004, 78(2): 922-9; J. Biol. Chem. 2005, 280(51):42149-55; J. Virol. 2006, 80(12): 5716-22) and to be a first-in-class maturation inhibitor with a potent activity against HIV-1.
Encouraged by these developments, medicinal chemists started exploring betulinic acid derivatives and related compounds intensively for their therapeutic activities. For example, the patent publication WO 2008057420 describes extended triterpene derivatives as antiretroviral agents; WO 2007141391 describes Betulin derived compounds useful as antiprotozoal agents; WO 2007141390 describes preparation of betulin derived compounds as antiviral agents; WO 2008127364 describes preparation of betulinic acid derivatives for use in antiviral and anticancer pharmaceutical compositions; US 20080207573 describes preparation of triterpene derivatives for therapeutic use in the treatment of viral infections; WO 2007141389 describes preparation of betulin derived compounds as antibacterial agents; US 20040204389 describes anti-HIV agents with dual sites of action; WO 2007/002411 describes antiviral compounds; CN 1861627 describes antitumor agents; WO 2006053255 describes novel betulin derivatives, preparation thereof and use thereof; WO 2009/082818 describes novel C-21 keto lupine derivatives preparation and use thereof; and WO 2006105356 describes methods of manufacturing bioactive 3-esters of betulinic aldehyde and betulinic acid.
Similarly WO 2009/082819, WO 2009/100532 disclosed 17 β lupine derivatives as anti-HIV agents.
Some more references disclose betulinic acid related compounds. For example, WO 2007141383 describes betulin derivatives as antifeedants for plant pests; U.S. Pat. No. 6,670,345 describes use of betulinic acid and its derivatives for inhibiting cancer growth and process for the manufacture of betulinic acid; WO 2002091858 describes anxiolytic marcgraviaceae compositions containing betulinic acid, betulinic acid derivatives, and methods of preparation and use; WO 2000046235 describes preparation of novel betulinic acid derivatives for use as cancer growth inhibitors and WO 2007141392 describes cosmetic and pharmaceutical compositions comprising betulonic acid and betulin derivatives.
Given the fact of the world wide epidemic level of AIDS, there is a strong continued need for new effective drugs for treatment of HIV infected patentis, disease conditions and/or disorders mediated by HIV by discovering new compounds with novel structures and/or mechanism of action(s).